This invention relates in general to sound isolation cabinets useful for recording musical instruments such as electric guitars, and more specifically to a sound isolation cabinet using complimentary sound sources to generate improved isolated sound.
It is very difficult to accurately reproduce an electric guitar""s xe2x80x9clivexe2x80x9d sound in an isolated space. However, it is very desirable to do so because isolating the sound allows the sound to be recorded without bothering other people such as neighbors in an apartment building. Also, isolating the sound prevents other sounds from interfering with the recording of the electric guitar sound as in professional recording situations where a live performance requires other loud instruments to play at the same time as the electric guitar.
Two approaches have been made to isolate an electric guitar sound. One is the direct approach where the sound is maintained as a purely electronic signal. The other is the xe2x80x9cisolation cabinetxe2x80x9d approach where the sound is reproduced acoustically in an enclosed space.
The xe2x80x9cdirectxe2x80x9d approach to recording electric guitars has been tried for many years. Many pre-amplifiers, equalizers and sound effects gadgets are available to enhance the direct signal from the guitar so that the processed signal can be directly used for recording, or for reproducing in headphones or for other purposes. However, none of the available direct equipment produces a sound as pleasing, or desired, as the tone achieved when the electric guitar is played at amplified volume through speakers. Since this mode is the way the electric guitar is played in a live concert, it is sometimes referred to as the xe2x80x9clivexe2x80x9d sound of the electric guitar.
One reason the direct approach fails to reproduce the live sound is that there is a xe2x80x9cspeaker effect,xe2x80x9d or coloration of the sound due to the speaker or speakers. Different speakers have different sounds and are sought after for different types of music according to the tastes of the particular musicians. For example, speakers such as the xe2x80x9cGreenbackxe2x80x9d speaker manufactured by Celestion International, Ltd., Foxhall Rd., Ipswitch Suffolk, England, are very desirable for gritty, distorted xe2x80x9crock ""n rollxe2x80x9d tones. The number and variety of speakers is large. Each adds a slightly different color to the tone. Apparently the complex wave effects of the speaker cone""s vibrating surface in air makes for a more interesting tone that is lost when using the direct approach.
Another reason that the direct approach fails to reproduce the live tone of an electric guitar is that some guitar tones are only fully realized at high output from an amplifier. For example, amplifiers made by Marshall Products, Ltd., Bletchley, England, are highly desirable for certain types of music, but certain of their tones are only realized when the amplifier""s power output stage is set to a high output level. Although the prior art uses resistive loading, inductive loading and other techniques to try to xe2x80x9csiphonxe2x80x9d off a direct signal from an amplifier""s power output, these methods fail to yield a sound that is, by many standards, even remotely close to the live sound.
Given the shortcomings of the direct approach, attempts have been made to produce xe2x80x9cisolation cabinetsxe2x80x9d which are little more than enclosed boxes containing a speaker and a microphone. The electric guitar output is amplified and fed to the speaker which produces sound that is picked up by the microphone. The signals from the microphone are routed to other external devices for audibly playing the sound, or recording the sound. Since the electric guitar is amplified and driving a speaker, this setup is the same as the live setup. However, these approaches have failed to produce a pleasing reproduction of the guitar tone. The reason for this is that the speaker is xe2x80x9cdampedxe2x80x9d or restricted in it""s freedom to vibrate because of the compression of air in a small volume necessary to contain the sound. To date, no isolation cabinet exists that can approach the live sound to the point where it can effectively be used to record a certain live-sounding guitar tones in professional recordings. For example, the Internet page xe2x80x9cwww.cybtrans.com/guitar/g101.htmxe2x80x9d includes a discussion on isolation cabinets, and the failings of some commercially available cabinets.
The present invention is a sound isolation cabinet that uses two or more speakers to generate complimentary sound waves within the sound-proof cabinet. The sounds generated inside the cabinet are detected by a microphone and sent to external device for recording or listening purposes. In one embodiment, two speakers are arranged side-by-side and mounted on a panel. The panel serves to section-off two chambers within the cabinet. The primary chamber is the chamber toward which the speakers are facing. The secondary chamber is the chamber within which the backs of the speakers are positioned. The speakers are connected to the input signal in reverse polarity of each other. Thus, during operation one speaker is pushing air outward while the other is pulling air inward. This complimentary generation of sound waves alleviates the muffling effect of the small isolated space and allows the speakers to generate sound as though they were in a much larger open area. Thus, the sound picked up by the microphone is very close to the desired xe2x80x9clivexe2x80x9d sound.
A preferred embodiment of the invention uses: a cabinet enclosure; an input for receiving an external electrical signal; first and second speakers positioned in the isolation cabinet, wherein the speakers are responsive to the electrical signal to produce sound by moving air within the cabinet; and a coupling between the input and the first and second speakers so that the air in the cabinet is moved in a complimentary fashion to produce sound within the cabinet in response to the electrical signal.